The United States Energy Information Administration has released data showing that the transportation of people and goods accounts for about 25 percent of all energy consumption in the world and that passenger transportation, in particular light-duty vehicles, account for the most transportation energy consumption. The share of transport in world energy consumption is expected to increase to 30 percent by 2040.
Self-generation of energy by transport vehicles using solar energy will reduce transport's foot print in the consumption of world energy. Another major drain on energy utilization in transport vehicles is aerodynamic drag. Depending on the geometry of a vehicle, aerodynamic drag may account for as high as 60% of its energy consumption. Reduction in aerodynamic drag would significantly reduce the environmental footprint of transport vehicles and result in major cost and environmental benefits due to reduced fuel consumption.
Prior art arrangements have been provided for reducing drag for an object comprising a vehicle of a given shape. A few of such type of arrangements include creating a plasma between a surface on the object and an area of laminar flow above the object.
Historically, plasma actuators have had very limited success in flow control due to a number of factors. The structure for any given drag-reducing unit based on traditional plasma actuators does not allow for seamless integration in a number of vehicle geometries. None of the prior art uses sensors to judge flow separation in a transport vehicle in real time. Neither do these take into account the most fundamental contributing factors to aerodynamic drag including vehicle speed, atmospheric temperature, coefficient of drag, Reynolds number, relative humidity, surface area of the transport vehicle, air pressure, and its reduction based on any one or more of these parameters. For example, it was determined that the creation of plasma on the surface of transport vehicles at low speeds, e.g., less than 25 mph, increased drag for most transport vehicle geometries. However, almost all prior art supports the activation of plasma actuators as soon as the vehicle starts moving.
DBD plasma actuators have a high electrical energy consumption that overrides the saved power from the skin-friction drag reduction. However, if an efficient design of DBD plasma actuators is used, then substantial power saving is achievable. Prior art has not been able to specify that efficient design as yet.
Active flow control technologies have not yet been adopted in controlling aerodynamic drag essentially due to the disorderly nonlinear nature of the key physical processes and because of the difficulty in monitoring or estimating the chaotic flow status and parameters accurately, resulting in a very challenging optimal control problem. Many other factors regarding deployment of actuators for drag reduction have not been considered by the prior art.
The ability of traditional plasma actuators in flow control at highway speeds is practically non-existent. Successful demonstration of vehicular drag reduction using plasma actuators at highway speeds has as yet not been reported.
U.S. Pat. No. 9,951,800 discloses a surface plasma actuator having a conducting wire attached to a surface of a target object and electrically insulated from the target object. Surface plasma is generated adjacent to the conducting wire by applying a pulse voltage to the conducting wire. This arrangement is particularly suited to the vanes in gas turbines. The wire structure is not suited for incorporation in transport vehicles.
U.S. Pat. No. 9,821,862 discloses a system, for controlling aerodynamics of a vehicle comprising multiple pairs of opposing plasma actuators positioned at lateral positions on an underside of the vehicle, wherein each pair of opposing plasma actuators comprises two electrodes. The plasma actuator may be configured as a small strip, similar in thickness to a strip of aluminum foil, having or connected to a glue layer for easy attachment to a transport vehicle body, and then connected to a power source. The plasma actuator is not interacting with another body component integral with the shape of a vehicle.
United States Published Patent Application No. 20180065690 discloses a plasma actuator including a first electrode disposed on a substrate, covered by a dielectric layer, and a second electrode disposed on the dielectric layer. The plasma actuator creates a plasma region, altering air flowing over the actuator. A particular structure for reducing drag is not shown.
Prior art arrangements have also been provided for directing electric current generated by photovoltaic cells to the transport vehicle. Most of these are restricted to the roof or part of the roof of the vehicle while some other structures do not blend seamlessly into the shape of the vehicle and increase aerodynamic drag. Also, the photovoltaic cells in most of these structures are single cell with a maximum theoretical efficiency of about only 33%. The solar arrays in prior art are not concealed and do not blend-in with the rest of the surface of the vehicle and early adoption was inhibited because of aesthetic reasons.
U.S. Pat. No. 6,517,148 B1 discloses a solar cover for a motor vehicle for the roof only with a transparent cover.
U.S. Pat. No. 6,474,729 B2 discloses a solar cover for a motor vehicle for the roof only with a carrier plate with a plurality of photovoltaic cells and a cover plate.
U.S. Pat. No. 6,337,436 B1 discloses a solar module for mounting on motor vehicles, which is provided with a top cover layer and a bottom cover layer, between which a solar generator is embedded which has plurality of electrically interconnected photovoltaic cells.
U.S. Pat. No. 5,545,261 discloses solar roof for motor vehicles with a solar generator having photovoltaic cells for supplying power to a power consumer and/or a battery and with a DC converter for impedance matching between the solar generator and the consumer and/or battery.
U.S. Pat. No. 5,154,481 discloses a vehicle roof with at least one cover that, alternatively, closes or at least partially opens an opening in a fixed roof surface of the vehicle, carries a solar power source for supplying power to at least one power consuming device.
U.S. Pat. No. 6,155,636 discloses a solar roof for motor vehicles having a cover with photovoltaic cells which are located between an outside cover plate and inside covering, at least one power consumer which is separate from the solar cover.